The present invention relates to a sharpener assembly for a food slicer and, more particularly, to a sharpener assembly configured for enabling pivotal movement of a sharpening wheel and a truing wheel toward opposite sides of a knife of a food slicer.
Typical food slicers have a base with a rotatable, circular or disc-like slicing knife mounter thereon, a gauge plate for determining the thickness of the slice and a carriage for supporting the food as it is moved past the cutting edge of the knife during slicing. The cutting edge of the knife tends to dull from use and therefore a sharpener is needed to sharpen the knife to maintain a good cutting edge for efficient slicing. Sharpening stones are typically brought against the knife""s cutting edge as the knife rotates in order to provide such sharpening. A variety of sharpening devices have been used in the past to provide such sharpening.
Many existing sharpening devices suffer from using complex arrangements to convert a rotational movement into two translational movements. Other existing sharpening devices require two steps, a first in which a sharpening wheel or stone is brought into contact with one side of the knife to sharpen, and a second in which a truing wheel or stone is brought into contact with the opposite side of the knife to debur the knife edge.
U.S. Pat. No. 5,591,072 which is assigned to the assignee of the present application provides a sharpening device which overcame the problem of having to move the sharpening device between an inactive or stowed position and an active or sharpening position. However, the construction provided is relatively complex and includes a large number of parts adding to the expense of manufacture. Canadian Patent No. 630,702 describes a slicer with a knife sharpener which includes sharpening wheels which can be positioned on opposite sides of a knife for sharpening, but as mentioned above, requires the sharpener to normally be stored in an inactive position when not in use and in such inactive position the sharpening wheels are not positioned on opposite sides of the knife. Further, the sharpener requires two handles to be operated in order to sharpen the slicer knife.
Another disadvantage of known knife sharpeners is that the sharpening stones or wheels typically need to be more abrasive than the truing stones or wheels used. This requirement adds to parts cost of sharpeners and requires a more exacting manufacturing process in order to assure that the wheels of appropriate abrasiveness are placed properly during manufacture.
Further, certain food slicers are adapted for use with more than one type of slicer knife, and different knives can have different attributes such as knife edge thickness. Many existing sharpener assemblies lack the ability to account for such differences between knife types.
Accordingly, it would be desirable and advantageous to provide a relatively simple sharpener assembly which is always positioned for sharpening when attached to a food slicer. It would likewise be desirable to provide a sharpener assembly operable to provide sharpening and truing simultaneously by a single rotational motion. Further, it would be desirable and advantageous to provide a sharpener assembly configured to permit the sharpening wheel and the truing wheel to have substantially the same abrasiveness while still providing effective sharpening. Still further, a sharpener assembly which enables adjustment of the amount of sharpening which is performed would also be advantageous.
In one aspect of the present invention a method of sharpening and truing a rotating slicer knife of a food slicer involves providing a rotatable sharpening wheel and a rotatable truing wheel on opposed sides of the slicer knife, the sharpening wheel and the truing wheel connected for pivotal movement toward the slicer knife upon rotation of a handle member. The handle member is rotated such that both the sharpening wheel and the truing wheel contact the slicer knife causing the sharpening wheel and the truing wheel to rotate. Relative rotation between the sharpening wheel and the slicer knife results in a sharpening grain acting inward along a cutting edge of the knife and relative rotation between the truing wheel and the slicer knife results in a truing grain acting outward along the cutting edge of the knife. The inward acting sharpening grain provides a more aggressive grinding action as desired for sharpening and the outward acting truing grain provides a less aggressive grinding action as desired for truing.
In another aspect of the present invention a sharpener assembly for a food slicer having a rotatable knife includes an assembly mount head having a recessed slot, the mount head including a through hole to the recessed. A frame having first and second spaced mount arms with a connecting member extending between the mount arms is provided, each mount arm including a through passage along its length. At least a portion of the connecting member is positioned within the mount head slot in alignment with the through hole. A first shaft extends through the through passage of the first mount arm and has a sharpening wheel connected to a first end thereof and a second shaft extends through the through passage of the second mount arm and has a truing wheel connected to a first end thereof. A handle is operatively connected to the frame connecting member through the through hole of the mount head for pivoting the frame. The subject assembly is preferably detachably connected to the base of the food slicer such that the sharpening wheel and truing wheel are normally positioned on opposite sides of the knife to facilitate sharpening as necessary by turning the handle to pivot the wheels into contact with the sides of the knife. Thus, a simple one-step rotation operation provides both sharpening and truing and there is no need for moving the assembly to an inactive position when it is not in use for sharpening and truing.
In yet another aspect of the invention a sharpener assembly for a food slicer having a rotatable knife includes a frame having first and second spaced mount arms with a connecting member extending between the mount arms. A first shaft extends from the first mount arm and has a first abrasive wheel connected to an end thereof and a second shaft extends from the second mount arm and has a second abrasive wheel connected to an end thereof. A first biasing member is positioned on the first shaft for biasing the first abrasive wheel away from the first mount arm and a second biasing member is positioned on the second shaft for biasing the second abrasive wheel toward the second mount arm. In the preferred embodiment one abrasive wheel is a sharpening wheel and the other abrasive wheel is a truing wheel and the force exerted by one of the biasing members on the sharpening wheel is greater than the force exerted by the other biasing member on the truing wheel. Such preferred construction facilitates using wheels having substantially the same abrasiveness for both the sharpening wheel and the truing wheel.
In a further aspect of the present invention a food slicer includes a base with a disc-like slicing knife mounted for rotation on the base and having a peripheral cutting edge. A knife guard extends about a portion of the peripheral cutting edge of the knife and includes first and second side portions extending along respective first and second sides of the knife. A sharpener assembly is detachably mounted to the base and includes a frame having first and second spaced mount arms with a connecting member extending between the mount arms, a first shaft extending from the first mount arm and having a first abrasive wheel connected to an end thereof, and a second shaft extending from the second mount arm and having a second abrasive wheel connected to an end thereof. The first abrasive wheel is positioned on the first side of the knife and the second abrasive wheel is positioned on the second side of the knife. The first side portion of the knife guard includes a first open region alignable with the first abrasive wheel and the second side portion of the knife guard includes a second open region alignable with the second abrasive wheel. This configuration provides a slicer with a sharpener assembly which is always in a ready position for sharpening.
The abrasive sharpening or truing wheels incorporated in to the sharpener assemblies may preferably be formed by a disc-shaped member having a knife engaging side which includes a recessed area surrounded by an annular abrasive surface, wherein the annular abrasive surface is frusto-conical in shape such that a central axis of the frusto-conical annular abrasive surface coincides with a central axis of the abrasive wheel.